1. Field of the Invention
The present invention relates to seed meters for metering seeds at a controlled rate into a furrow in the ground over which the seed meter is traveling, and more particularly to a hollow, elongated seed tube for directing seeds released by the seed meter into the furrow in the ground below.
2. History of the Prior Art
It is known in the field of agricultural equipment and machinery to provide seed meters which meter or dispense individual seeds into a furrow in the ground at a controlled rate in conjunction with associated apparatus for creating the furrow and then moving loose soil back into the furrow after the seeds have been deposited therein. There are various types of seed meters including the mechanical type in which individual seeds are plucked from a seed mass and discharged from the meter for deposit within the furrow by mechanical devices. Still other types of seed meters are of the air type in which a pressure differential is employed, particularly in conjunction with a rotating seed disk or similar device, to pick up seeds from the seed mass and then discharge them from the meter into the furrow. Air seed meters can be of the positive airflow type in which the seeds are picked up by the seed disk and held thereon by blowing air. Air seed meters can also be of the vacuum type in which a reduced pressure is communicated to the seed disk in a manner enabling the disk to pick up and carry individual seeds thereon with the assistance of the reduced pressure.
An example of a vacuum seed meter is provided by a copending application, Ser. No. 546,834, now abandoned, Lundie et al, VACUUM SEED METER, filed Oct. 31, 1983 and commonly assigned with the present application. The Lundie et al application describes a vacuum seed meter in which a rotating seed disk is mounted within the hollow interior of a housing so as to have a seed mass disposed on one side thereof and a source of reduced pressure coupled to a vacuum chamber at the opposite side of the disk. The reduced pressure communicates with a plurality of seed cells recessed in the side of the disk facing the seed mass via apertures extending through the thickness of the disk from the bottoms of the cells. The reduced pressure assist the cells in picking up individual seeds from the mass and transporting them to a seed discharge area sealed off from the reduced pressure to provide for release of the seeds carried in the seed cells. The released seeds fall through a discharge chute into a furrow in the ground formed by an opener unit mounted in conjunction with the seed meter.
With seed meters of any type it is desirable that the seeds be metered in such a way that they are generally equidistantly spaced along the length of the furrow. This requires not only that the seeds be metered from the seed meter in accurate fashion but that they be directed into the furrow in a manner which minimizes bouncing of the seeds along the ground.
In the case of an air seed meter employing a rotating seed disk, the individual seeds carried by the seed disk are typically released from the disk at a desired location within the circular path of the disk by isolating the pressure differential from the seed disk in that region. In the case of the vacuum seed meter described in the previously referred to Lundie et al application a seal surrounding and forming a part of a vacuum chamber at one side of the seed disk is configured so as to isolate a portion of the seed disk opposite a seed discharge area from the reduced pressure in the vacuum chamber. The seed discharge area lies at a portion of the side of the seed disk within the hollow interior of the housing surrounding the seed disk. The interruption of communication of the reduced pressure to a portion of the seed disk allows seeds carried within recessed seed cells in the disk with the aid of the reduced pressure to be released from the cells. The individual seeds as so released fall under the effects of gravity through a seed discharge chute at the bottom of the seed meter to the furrow in the ground below.
Seed meters travel over the ground at some nominal velocity during the metering process. Typically, a plurality of the meters are mounted in parallel on the elongated frame of a wheeled agricultural implement which is towed over the field to be planted. If the individual seeds are released from each seed meter for essentially vertical, straight down movement into the furrow below under the effects a gravity, the seeds as they strike the ground have a velocity which has a horizontal component due to the motion of the seed meter over the ground. This horizontal velocity component frequently causes the seeds to bounce laterally in a direction away from the intended landing areas, resulting in inaccurate and nonuniform distribution of the seeds within the furrow.
It is therefore desired that the horizontal velocity component upon seed impact with the ground be minimized or eliminated so that any seed bounce will be essentially vertical and the seed will eventually settle in the desired landing area within the furrow. This may be accomplished by providing each seed meter with a seed tube configured so as to compensate for and cancel out the effects of the horizontal velocity component. Thus, while not shown in the previously referred to Lundie et al application, the vacuum seed meter described therein is typically equipped with a seed tube designed to minimize or eliminate the horizontal velocity component of the individual seeds as they strike the ground. Such seed tube which is coupled to the seed chute at the bottom of the seed meter so as to extend downwardly therefrom and is curved in a direction opposite the direction of movement of the seed meter over the ground. The seeds are thereby caused to exit the seed tube in a direction providing them with a horizontal velocity component generally equal to and opposite the horizontal velocity component provided by movement of the seed meter over the ground. The seed tube is relatively straight along an upper portion thereof and has a constant, fixed curvature along a lower portion. The straight upper portion of the seed tube is aligned in accordance with the direction of seed release by the meter to provide relatively smooth receipt of the seeds within the seed tube. The lower portion of the seed tube is curved by an amount sufficient to release each seed at a desired angle relative to the vertical so as to provide the seed with a horizontal velocity component capable of compensating for the horizontal velocity of the seed meter over the ground.
It has been found that while seed tubes of the type described are somewhat effective in minimizing or eliminating the horizontal velocity component from seed discharge, such seed tubes can introduce problems of their own which detract from the advantages of using them. A major problem with such seed tubes is the tendency for seed rattle or seed bounce to occur within the tube. This describes the situation in which the seeds undergo excessive bouncing within the tube with the result that they have varying residence times within the seed tube and exit from the tube at differing and unpredictable angles. These factors have a harmful affect on uniformity of the metering process. Different residence times of the individual seeds within the seed tube results in nonuniform timing of discharge of the seeds from the seed tube. Varying seed discharge angles from the seed tube which result in nonuniform seed distribution, even in situations where seed residence time within the tube is uniform.
Accordingly, it would be advantageous to provide an improved seed tube for use with seed meters.
It would furthermore be advantageous to provide an improved seed tube which in addition to compensating for horizontal seed velocity due to motion of the seed meter over the ground minimizes seed rattle or bounce within the tube so as to provide relatively uniform seed residence time within the tube and a relatively uniform angle of seed discharge from the tube.